For my daughter's fourth birthday in July, we had a princess "pool" party in our backyard. Everyone had a great time and the party was a huge success. I think the reason it was so successful is (1) I let my daughter plan it her way and let her participate in every aspect of the party preparations; and (2) I didn't try to make every little detail stay in theme; and (3)I didn't worry whether everything was perfect. The invitations were the Disney Little Mermaid invitations.  My daughter put stickers on them and delivered them in her wagon to the neighbor kids we invited (11 total, including my 3 kids). The decorations were pink and purple streamers on our stairs, put up by my daughter and I, bunches of baloons, and some cardboard cutouts of various princesses from fruit snack boxes, coloring book covers, and previous princess and barbie gifts. For the table cover, I used some leftover tweety bird paper tablecloths from my daughter's last birthday party (mostly covered in hearts and flowers).  For entertainment, we rented a Disney princess moon bounce, inflated our kiddie pool and set out some bath toys and water guns.  No crafts or games were necessary - the kids had a great time just playing. For food, we had barbequed hamburgers and hotdogs, chips, salad, chili, fruit, bags of goldfish and cookies, and drinks. We had a pinata filled with toy trinkets and candy (more toys than candy; the kids usually like them better and can only pick up so much candy). Both the pinata and the desert plates were the Barbie Princess and the Pauper theme - selected by my daughter. Instead of a cake, we had three kinds of cupcakes (homemade) - vanilla, strawberry and chocolate. My children put sprinkles on the top and everyone loved them.  The one thing I did wrong was to make the cupcakes the day of the party. I should have done it the night before.  Favors were little purple bags with bouncy balls, sidewalk chalk in Disney shapes, mini slinkies, princess or batman stickers, and rings. The bags doubled as pinata candy bags, so everyone went home with a bag full of treats.   The parents stayed for the party too and had a good time talking, eating, relaxing, and in some cases, fighting with the water guns! while the kids played. The party lasted about 3 hours, took minimal planning, and really made my daughter feel special.